FOXP1 haploinsufficiency: Phenotypes beyond behavior and intellectual disability?

Area of Science:

• Genetics and Developmental Biology
• Molecular Biology

Background:

• Forkhead box (FOX) transcription factors, including FOXP1, are crucial regulators of development, metabolism, immunity, and carcinogenesis.
• Human FOXP1 mutations are linked to developmental disorders such as intellectual disability, autism spectrum disorder, and congenital anomalies.
• In mice, Foxp1 is essential for the development of spinal motor neurons, lymphocytes, cardiomyocytes, foregut, and skeleton.

Observation:

• This study reports two individuals with novel FOXP1 variants (NM_032682.5:c.975-2A>C and NM_032682.5:c.1574G>A).
• One individual presented with a lung disease similar to neuroendocrine cell hyperplasia of infancy (NEHI).
• The second individual exhibited a skeletal disorder characterized by undertubulation of long bones and recurrent fevers with flushing and edema.

Findings:

• The identified novel FOXP1 variants are associated with previously unrecognized clinical features.
• These findings expand the spectrum of phenotypes linked to FOXP1 mutations.
• The study hypothesizes that FOXP1 mutations may affect additional tissues, contributing to diverse clinical presentations.

Implications:

• These observations suggest that FOXP1 plays a broader role in human development than previously understood.
• Further research and patient ascertainment are needed to confirm the attribution of these novel features to FOXP1 mutations.
• The variable expressivity of these additional features may be influenced by stochastic developmental variations, highlighting the complexity of genetic disorders.